<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<script>

    console.log(123||456);   //123

    //注意 &&  的 优先级大于 ||
    console.log(123||456&&0)    //123
</script>
<body>

</body>
</html>